KrausMotorSports Posted December 26, 2012 Report Share Posted December 26, 2012 Since I've bought this truck I've had multiple issues and I've come down to this. Vacuum issue. Truck wants to stall after small revs, turning the wheel, and after braking( also peddle feels spongy and somewhat hard to stop) Truck originally had a side mount whipple and replaced all original hoses to original locations( hoses are in working order, not cracked or kinked) vacuum lines and switched valves covers back. Im in the process of finishing my triple pillar with vacuum/boost guage so I will know more hopefully by Saturday. Any ideas? I'm checking the usual but stuck at work and can't help but to think of what else it could be? Quote Link to comment Share on other sites More sharing options...
desrtrat Posted December 26, 2012 Report Share Posted December 26, 2012 check your break booster, may have a small leak inside . what are you showing on a vacuum gauge, what is your idle set at, and are you running a stock cam? Quote Link to comment Share on other sites More sharing options...
KrausMotorSports Posted December 26, 2012 Author Report Share Posted December 26, 2012 If I remember correctly when I was running the whipple I saw maybe 12-14 in of vacuum but that's a guess. It is a stock cam. Plus my guages were reading funky drop off stop working etc... Who ever did the original install was horrible. Quote Link to comment Share on other sites More sharing options...
Blazerdave2000 Posted December 26, 2012 Report Share Posted December 26, 2012 Bad pcv valve? My old green truck would stall like that found a stuck pcv valve changed it and never did it again. Also since I have had my stall converter in my truck I notice it kind of Boggs down and rpm drops quick when going slow or just touching the gas ever so slightly. I don't know anything I'm just questing here from personal experience lol. Quote Link to comment Share on other sites More sharing options...
Fireman31 Posted December 27, 2012 Report Share Posted December 27, 2012 Any idea what the idle speed is set at? Kind of sounds like a low idle speed issue.... Also, spongy brakes have been a complaint with these trucks here for 10 years, do a search here and you will find a ton of useful info in regards to fixing the issue.... Quote Link to comment Share on other sites More sharing options...
Blown 346 Posted December 27, 2012 Report Share Posted December 27, 2012 If you can get a smoke a source, or just a cheap cigar. Puff off the cigar and gently blow around the intake, anywhere a vacuum leak would be. (Make sure to not have strings off you hoody in the engine bay) You will find any leak with smoke. I would also check the intake manifold, there are rubber gaskets under it, throttle body etc. Quote Link to comment Share on other sites More sharing options...
chpspecial Posted December 27, 2012 Report Share Posted December 27, 2012 Bad pcv valve? My old green truck would stall like that found a stuck pcv valve changed it and never did it again. Also since I have had my stall converter in my truck I notice it kind of Boggs down and rpm drops quick when going slow or just touching the gas ever so slightly. I don't know anything I'm just questing here from personal experience lol. Our trucks don't have PCV valves, just on orifice on the drivers side valve cover with a baffle. This issue does seem vacuum related, stock the cam should idle at around 16" of vacuum. Quote Link to comment Share on other sites More sharing options...
KrausMotorSports Posted December 27, 2012 Author Report Share Posted December 27, 2012 (edited) If you can get a smoke a source, or just a cheap cigar. Puff off the cigar and gently blow around the intake, anywhere a vacuum leak would be. (Make sure to not have strings off you hoody in the engine bay) You will find any leak with smoke. I would also check the intake manifold, there are rubber gaskets under it, throttle body etc. I've got a few stoggies I picked up from the Dominican last year! Lmao and I sure as heck don't want to ruin my ss silverado hoodie! I've thought of the gaskets possibly being bad. I searched last week and found the mushy brake topics. Lol and I wished I saw 16" of vacuum. Weather has been crappy and cold so I should know more by saturday. Hellooooo 4 day weekend! On a second note I do have a Preditor Diablo sport tuner. "not for tuning just diagnostics" lol I know there horrible. Idle goes between 530 and 480. When it what's to stall but hasn't yet I see around 350rpm's 9% TP angle 0.891 b/m MAF 5.1 psi MAP Edited December 27, 2012 by KrausMotorSports (see edit history) Quote Link to comment Share on other sites More sharing options...
KrausMotorSports Posted December 30, 2012 Author Report Share Posted December 30, 2012 Ok checked all the hoses -there good but when I removed and quickly reattached brake booster and idle went up. I'm also reading about 2" of vacuum at idle and when I give a little acceleration it goes to about 10" of vacuum. If I basically flash rev the gas it reads boost! But I dont hear the whine? Lol any ideas guys? My wiring is correct on my guage pillar. Also reading a 14.8 AFR at idle. Quote Link to comment Share on other sites More sharing options...
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